A novel tool for floating offshore wind substructures design: Validation and definition of design guidelines

An efficient frequency-domain numerical tool for the preliminary design of Floating Offshore Wind (FOW) substructures has been developed, investigated, and validated against a state-of-the-art time-domain method. This tool, focused on floating substructures and particularly semi-submersible platforms, aims to expedite the design process. Its originality lies in coupling two novel methods to determine hydrodynamic loads: one estimates linear hydrodynamic coefficients, and the other predicts second-order wave loads. Combined with a simplified frequency domain response model, it enables rapid assessment of the dynamics of various platform designs, thus accelerating preliminary design. To minimise computational costs, certain simplifications have been adopted, such as assuming negligible interaction effects between platform members. This assumption enhances the method's accuracy, particularly when platform columns are spaced further apart for a given diameter. Despite these simplifications, the tool has shown to produce results comparable to existing methods regarding FOW structures’ dynamic behaviour, helping identify the most suitable platform designs for further evaluation in advanced design phases. Its notable efficiency also makes it suitable for sensitivity analyses, enhancing understanding of FOWT dynamic behaviour and quantifying the influence of different parameters on platform design.